1. Field
This application relates generally to wireless communication and more specifically, but not exclusively, to an access point identifier configuration scheme.
2. Introduction
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (“CDMA”) systems, time division multiple access (“TDMA”) systems, frequency division multiple access (“FDMA”) systems, 3GPP Long Term Evolution (“LTE”) systems, and orthogonal frequency division multiple access (“OFDMA”) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless access terminals (e.g., user equipment). Each terminal communicates with one or more access points (e.g., base stations, eNodeBs, etc.) via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from an access point to an access terminal, and the reverse link (or uplink) refers to the communication link from an access terminal to an access point.
Each access point in the system is assigned an identifier (e.g., a physical cell identifier, PCID) that identifies the access point and its corresponding cell (or sector). In some implementations an identifier comprises a pilot pseudorandom noise (“PN”) pattern (or offset). For example, a PN pattern may be a known signal pattern that appears as noise when viewed out of context. Accordingly, a pilot PN of an access point is the pseudorandom noise pattern of the access point and may be used to identify the access point to access terminals and other access points. Here, an access terminal in the system acquires the identifiers broadcast by nearby access points to learn which access points are in the area as well as the system parameters utilized to properly acquire a connection with each access point. In addition, access points may learn the identifiers of neighboring access points to facilitate hand-off of access terminals between cells.
Typically, a fixed quantity (e.g., 504) of access point identifiers is defined in a given system. Accordingly, in conventional network planning, an operator (e.g., an access point vendor, an administrator of a network, etc.) carefully assigns identifiers to access points to avoid conflicts or collisions. For instance, if two or more neighboring access points or access points within communications range of an access terminal possess identical or similar identifiers, a collision occurs. Such collisions may result in significant interference on a channel and may result in service disruption. To mitigate these collisions, identifiers may be dynamically configured (e.g., capable of change) based upon topology change of a network. However, it is preferred that dynamic network reconfiguration rarely be performed due to the associated service interruption.
In situations only involving stationary access points (e.g., access points at fixed locations), identifiers may be assigned to minimize or avoid collisions. For example, neighboring access points may be assigned identifiers such that, even with update procedures, no collisions occur.
In situations involving mobile access points or relay stations, network planning may be challenging. As a mobile access point changes locations (e.g., travels with a train, bus, boat, airplane, or other vehicle), it encounters different macro cells served by stationary access points. As movements of a mobile access point may be impractical to predict, collisions may occur if a mobile access point approaches a stationary access point with a similar identifier or two mobile access points with similar identifiers come into range of one another. Accordingly, there is a need for effective techniques for avoiding collisions in wireless networks.